... .8,8.8.. Special screw,special head screw,special machine screw 1.What’s the specification of our Products ? ... iron,such as 1022,1018,1010,1008,1015...Medium carbon steel are 35k,45#,10B21,1035,CH38F,1039, ... in most of places such as drywall,concrete,chipboard,machine,wood...2)Main export market:North America,South America ... to call me any time !Tel:+86-15917002605 Carbon steel special head machine screw